Band Practice
by LittleSparrowBek
Summary: The Infernal Devices trio join up with The Mortal Instruments gang to form a band. Jace on keyboard, Jordan doing vocals, Simon rocking out the guitar, Jem playing the violin and all of it wrapped together with the lyrical genius that is Will. What mischief will they all get up to together? Hope you enjoy!
1. Chapter 1

**Hi! So, after reading City of Heavenly Fire** **we were forced to** **do exams (so cruel)** **and as we were studying my friend came up with this incredible idea. So I am simply putting it into a story! **

**A few things need to be said; First this story hasn't got any major spoilers from CoHF (I don't think) but I will have some pretty big ID spoilers. So if you haven't finished that then you should before reading this**. **However you should read all TMI and ID just cause they are amazing!**

**Ok, secondly; The setting of this story is rather confusing (even to me) so it is NOT really set at anytime as it does not take place during either of the plots. BUT having said that there are times where you will need to know what has happened in both series. It is not a part of the series but I'm assuming you've read the books (not CoHF that wouldn't be fair) **

**And lastly; the couples are JacexClary SimonxIsabelle MaiaxJordan AlecxMagnus and JemxTessa (I'm so sorry all fellow Wessa fans /3 ) **

**Right! Sorry REALLY long AN. But they are pretty important. Also this story takes a while to set up so bare with me. If you're are confused about anything I've said (I wouldn't blame you) then ask me :)  
So here you go! Hope you enjoy it.**

**Little Sparrow **

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Jace had never heard of a more idiotic idea. Though, it wasn't that surprising, considering it had come from Simon. The only reason Jace had given it any thought was because of the way Clary had looked as she bounded up to him before training the day before, her green eyes sparkling. Her red hair was bouncing with her steps and her smile; an excited and slightly mischievous smile left no option for Jace to say no.

After Clary had finished explaining it to him, Jace simply laughed at her. That was before he realised she was serious.

"Not happening." Jace told her as he made his way over to the stand where a variety of swords waited to be used.

"Come on Jace, it's a great idea!" Clary argued as she pulled her blue hoddie over her head and put it on the ground next to her bag. Jace watched her with a flat expression as she twisted her hair into a knot on top of her head.

"No," Jace said in a bored voice, "it really isn't."

Clary huffed at him and strode over to the swords. She picked up a simple short sword and turned to face Jace a spark in her eyes. "Fine. How about this?" She spun the blade in her hand, not as skilled as Jace but it was clear she was made to be a fighter, a shadowhunter. "If you win, I'll tell Simon you said no and never bring it up again."

Jace grinned at her knowing where she was going. "And if _you_ win?"

"You say 'yes' to Simon and help me persuade the others." Clary puffed out her chest and held her head high. Jace's grin turned into a full smile.

"You really want to fight me?" He asked amused. Clary was amazing; she was brave and strong and one of the best shadowhunters Jace had ever seen. But they both knew who would win this fight.

"Do you doubt me, Jace?" Mock hurt filled her face.

"Never." Jace's hand hovered over his sword. He picked it up and turned to face Clary who was already waiting on the sparing mats the smile still on her face.

Jace was not going to go easy on Clary. He would not lose to her, not when his manly pride was at stake. There was no way he was going to be a part of Simon's stupid band.

OoOoO

The short sword felt light in Clary's hands. Her feet felt steady beneath her and her heart was beating slow and steady. She could do this. Sure, Jace was probably one the best fighters in the world, but Clary had made Simon a promise. And she would not let Jace win without trying her best. Not to mention the giddy feeling she got thinking about Jace being on stage, his delicate fingers creating the most amazing music.

"Ready?" Jace was watching her carefully; assessing her stance and grip on her weapon. This was a training session after all.

Instead of answering, Clary positioned her body into a crouch, like Jace had taught her, knees bent and ready to move. She took two deep breaths in through her nose and exhaled through her mouth. Jace copied her stance and held his sword out in front of him.

Clary was momentarily distracted by his beauty. She didn't think she could ever grow tired of how his messy golden hair, a little shorter then she remembered, was stuck up as if he hadn't brushed it after sleeping. Or how his eyes gleamed with excitement and amusement. Or, Clary's eyes drifted down his body, how he looked in his training gear.

"Are you seriously checking me out in the middle of a fight?" Jace was eyeing her as if she had broken the most important rule. It was clear he was trying to be professional, but Clary could hear the laughter and slight cockiness in his voice.

"Technically it's the start of the fight; no one's moved yet." Clary pointed out while trying to focus on Jace's movements rather than appearance. He had begun circling her, holding his blade pointed towards her in his left hand. She mimicked his footing, _left cross over right, light on your feet, knees bent,_ Clary spoke to herself the words Jace had spoken to her only last week.

She barely caught Jace's smirk before he leapt forward and slashed at her. He was precise with his movements; they didn't want to slice each other to ribbons. Clary sprang back, the blade missing her sword by centimetres and landed less gracefully then she would have liked. Jace regained his posture and gave her a quick nod of approval for her dodging.

Bending his knees Jace made small circles in the air with his sword taunting Clary with a mischievous gleam in his eyes. Clary weighed her sword and set her jaw. Just as Jace had, she moved toward him keeping her sword up as a barrier between Jace's body and her own. Jace parried her bow; his blade sliding against hers to the hilt. Clary pushed against him with all her strength but it didn't seem to faze him. Instead Jace leaned in close so that Clary could feel his breath on her face and smiled at her.

"Does this mean you have to break poor Simon's heart?" Playful sarcasm in his voice. Clary scowled at him.

With a cry of irritation she pushed Jace back spinning to her right and away from Jace. Clary turned to face him again and felt a smile on her lips; Jace lifted one eye brow and shifted his blade from his right hand to his left and back again.

For what felt like forever, they stood eyes locked, before they both moved at the same time. Jace swing his blade above his head, Clary going anticipating this moved her blade so that hit would hit Jace just below his knees. Neither of them landed their blow. There was the loud clang as the metal slammed together.

Clary looked down to where her sword connected with Jace's. He must have moved at the last second, something that didn't really surprise Clary, because now they stood bodies almost touching. Only their blades between them. Clary lifted her eyes to see Jace; who was already watching her. His eyes scanning her face for a sign to move. She didn't give it though. Instead a small irrational idea came to her. The sensible side of her knew it would not end well but it was drowned out by her promise to her best friend. And it defiantly had nothing to do with the fact that Jace's hair was clinging to his temples with sweat or that his gold eyes were alive and content. And absolutely not how his lips were parted slightly. Clary told herself that it was for Simon.

"Clary?" Jace whispered and went to open his mouth to ask her something. Clary took the opportunity and reached up on her tippy toes. She maintained a strong grip on her weapon as she pressed her lips against his.

Jace's body went ridged with surprise. Clary's hand twitched, _not yet_, she told herself_._ A second later Jace gave in to the kiss and Clary felt the pressure from his blade lessen. Not completely, but enough that she had to act._ Now!_

Clary leaned into the kiss more, trying with all her will power not to become caught up in the familiar feel of Jace's lips. At the same time she flicked her wrist remembering how Izzy had showed her how to disarm someone. She used the swords hilt to protect her hand as she hit Jace's blade out from between them. It landed with a loud crash a few feet away from where they were still locked together. At the sound Jace pulled away and stared at his fallen sword in amazement. When he looked back at Clary she was grinning.

"I won!" Clary cried with glee which made Jace glare at her.

"You cheated." He snapped as he grabbed her sword from her grip.

Clary placed her hands on her hips and narrowed her eyes at Jace. "I didn't. You should never get distracted Jace. Wasn't that one of you first lessons?" She asked.

Jace placed both swords back before turning to Clary. He didn't look angry anymore which made some of Clary's resolve falter. As he approached her she began to step back away from him.

"Are you running from me Clary?" Jace asked with a grin.

"Are you going to do it?" She asked instead of answering. Jace sighed.

"Fine. But if Simon's friends are there then I'm out." Clary grinned at him and reached for her phone to tell Simon that Jace was in.


	2. Chapter 2

Chapter2

OoOoO

Simon hung up on Clary who was apparently in 'deep trouble' with her boyfriend. Simon wondered how she had persuaded him. Not that it mattered any more, Jace was done and Simon had other people he needed to talk to.

"Did he say yes?" Simon looked up at Izzy's dark eyes and nodded, "I knew he'd say yes if Clary asked him."

Simon watched the dark haired girl as she inspected her golden whip that was coiled around her arm. They sat across from each other at Taki's, Isabelle with a milkshake in front of her, Simon hadn't ordered anything.

"Hey Izzy?" Despite Clary and Jorden's encouragement this whole thing felt like it wouldn't work. "Do you really think this a good idea?"

She took a long sip of her drink before smiling at him. "Sure I do! Now you just need a few more people and you're all good."

Simon was thinking, "We would need a manager and I've never been good at writing lyrics."

"I think I know who would make a great manager. As for the lyrics, you can't do much worse than your friend. What was his name…? Erin?" She narrowed her eyes in thought.

"Eric. And yeah, but who is good with words?" Isabelle shrugged as she stood.

"I don't know," She put some cash on the table and smiled at Simon, "but I'm sure you'll figure something out." Isabelle made her way over to Simon and kissed him quickly before grinning. "I'll see you later with everyone else. Okay?"

"Yeah," Simon frowned still thinking, "see you then."

Who was he going to get? Jace played the piano, Jorden could sing, Simon himself was on guitar and Clary had already agreed to design a logo. Something she was very excited about, going off about how she never got to draw anymore. But out of everyone there was no one he could think of that fit who could put words together and create something decent.

Sighing about his dilemma, Simon stood and pushed his chair in before walking out of the restaurant.

OoOoO

"How dare you?!" The young man looked over to his friend and shook his head in exasperation, "They were your brethren, your brothers!" The dark haired boy yelled with in an over dramatic manner; waving his hands about and pacing back and forth along the water's edge. "Filthy, carnivorous, bloodthirsty little beasts!"

"Will," The young man's gaze shifted to the poor undeserving birds, "leave the ducks alone."

The boy spun on his heels to face his companion, his face full of fury and his blue eyes blazing. "Did they leave those pies alone Jem?" Will turned back to the water and glared at the ducks. He brought two fingers to his eyes then pointed at the confused birds, "I'm watching you."

Jem sighed. He knew central park probably wasn't the best place to come, but there had been a slight issue regarding a pixie who was feeding mundane children faerie food. Since they were already there Jem and Will decided it was their duty as shadowhunters to intervene, but it meant they had to inform the New York institute, something Jem hadn't thought they would be doing on a holiday to Tessa's old city. So far though, they had yet to deal with the issue because some poor innocent duck had the misfortune of crossing Will's vision.

"Will, we should deal with this pixie," Jem started.

"You're right." Will reached for his knife, "We don't want any children running around with antlers on their heads. I pity anyone who has experienced such a fate." Will gave the ducks one last cold stare before moving to follow his parabatai.


	3. Chapter 3

**So here's chapter three! enjoy! Little Sparrow xoxo P.s This chapter contains huge spoilers from all the books both TMI and ID so pelase finish them first, I dont want to ruin anything! Thankyou**

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Chapter 3

"I don't understand why we couldn't have dealt with it ourselves."

"You know as well as I do, Will, that we have to inform the shadowhunter's of the New York institute before we do anything." Jam spoke calmly as the two walked briskly towards the abandoned looking cathedral. To Jem however, it was beautiful, once the glamor was gone from his mind.

Behind him Will muttered, "Then the New York shadowhunters should do their job."

Jem laughed. "That's why we are here; to tell them there is an issue." He looked over his shoulder at Will, "You're just annoyed because you won't get to take credit for saving those poor antlered children."

Will shock his head. "Now, now Jem," he spoke very seriously, "Antlered children are nothing to joke about." He pushed past Jem and up to the Institute doors. "Right, shall we knock or let ourselves in?"

Before Will could open his mouth to say the words that would grant him access into the cathedral, Jem pressed the bell.

"You're no fun sometimes." Will said to Jem, but not without affection.

Jem simply ignored him, a tactic that seemed to work best on Will, and waited for the door to open. After five minutes of Will's impatient tapping Jem gave in.

"Perhaps they're not home?" Will offered unhelpfully.

"Fine. You open it." Jem used his hand to indicate at the door. Will grinned a fox-like smile at him.

He shrugged, "We could have saved five-"

"Open the door Will," Jem sighed.

"Fine." Will walked up to the door and placed his hand on the wood, "I, William Herondale, brother to the Niphlim, ask permission to enter-" The door clicked once before it gave out under Will's hand.

Together the two boys made their way into the foyer of the institute. There were dusty pews running all the way up in rows. At the far side of the room was a metal grate.

"Looks like we're going up." Will strode forward and pressed the button to call the elevator down. Not long after the sound of metal grinding against metal signalled the arrival of the elevator. Jem pulled open the grate and both boys stepped inside.

"How long do you think she'll take?" Will asked. His eyes shone the way they only did when he was worried about Tessa. Jem smiled; she was the only one who could bring out that side of Will. Despite their previous relationship Will was remarkably happy with Jem and Tessa being together. When Jem had asked him if it bothered him at all, Will had smiled and said that he had had his time with her and that there was no one other than Jem who he would allow to be with his Tess.

"She needs to deal with her past. It must be painful for her to come home to nothing." Jem said. Tessa had left them once they arrived in America. She said she wanted to visit her Aunt's grave and sort out her feelings. Jem understood her longing for closure and had not pushed her on the matter. Will hadn't either though Jem knew he was worried about her.

"I hope she's ok." Will's voice was soft and gentle.

"As do I." Jem replied.

There was a moment of silence before the elevator came to a halt with a clang. Will pulled the grate away to reveal a long corridor. Expensive carpets lined the floor and the whole place seemed efficient but nice. It was clear the owners had made this their home the same way the London institute had.

Will looked at Jem, "Shall we?"

Will and Jem made their way down the hall in silence, neither one wanting to call out and disrupt anyone. It was clear from Will's expression that he had no clue where they were meant to go. Jem was about to call for assistance when something brushed his leg.

He flinched at the contact and turned around to see a mound of mattered grey fur. Warmth filled Jem at seeing his old friend again. As he bent down the cat lifted his head and the two made eye contact.

"Hello Church." Jem laughed with affection and happiness as the cat purred and snuggled into him farther.

"Oh no," Jem heard Will groan, "I thought Magnus got rid of that cat." Unlike Will Jem was over joyed to see the cat and even more pleased that he remembered him. "Of cause," Will said, coming to some conclusion, "Magnus took it New York didn't he?" Will sighed.

"Can you take us to the head of the Institute Church?" Jem asked the cat who looked back at him with intelligent eyes before pulling away from Jem. He walked past Will flicking his tail towards him and distaste before turning a corner at the end of the passage.

The boys shared a brief look before they harried after him.

Church led them to a door that looked much like all the other doors and sat looking up at Jem. He gave a small but annoyed 'meow' when Will went for the door knob. Jem laughed and bent down to pat the cat.

"Thankyou Church." Jem said. Will huffed and knocked on the door loudly. Jem rose from the ground as it swung open.

A middle aged woman looked at them with surprise. Her hair was black and pulled back into a tight bun that sat in the middle of her head. Her surprise was gone after a few seconds and was replaced by a small frown.

"How may I help you gentlemen?" She looked them both over, "And if I may ask how did you get here?"

"The Institute is a place where any shawdowhunter is welcome-"

"My name is James Carstairs," Jem interrupted Will before he could offend her, "This is my parabatai Will. We are shadowhunters of the London Institute." Her expression softened slightly as she offered her hand.

"Maryse Lightwood, head of the New York Institute." They both flinched with surprise at her name.

"Lightwood?" Will inquired. Maryse shifted her attention to him with distaste in her eyes.

"If you have come to confront me about my past wrong doings I would appreciate it if you left."

Jem registered hurt and confusion in Will's eyes before he spoke, "Ms Lightwood-"

"Maryse," She corrected, her tone crisp, "Please, come in." Jem paused and nodded in thanks. Once seated in what Jem assumed to be the library, he continued.

"Maryse, we're here to inform you of a crime against the accords." Jem looked to Will who had decided not to sit and instead was standing next to Jem. Both boys were placed across from a large desk that was held up by carved angels. It was a truly tragic sight, Jem thought, to see an angel on their knees.

"And what would that be?" Maryse was seated behind the desk, her face tense and eyes cold.

"A faerie, well, pixie to be exact," said Will, "Was in central park giving children flowers to eat."

Maryse sighed. It was a heavy almost sad sigh. "Why must they always break the law?" She asked to herself. But Jem answered anyway.

"It is their nature. Though I do not condone their behaviour I can understand why they do it." Jem looked the elder women in the eyes, "It is not our place to judge as harshly as we do. As shadowhunters we should be able to respect what they are."

Maryse eyed the young boy before with new-founded respect. "I agree with you." She said surprising Jem, "But as shadowhunters we must not allow this to slip for the possibility that it could escalate."

"So what now?" Will asked.

"I will send two shadowhunters to deal with it." Maryse stood and pressed her palms against the desk. "I thank you for reporting this. Trust that it will be dealt with."

Will looked desperately at Jem. It was clear that he wanted to deal with this. It was also clear that, surprisingly, Maryse liked Jem more than Will.

"If we may, could Will and I accompany your shadowhunters? We could show them where it was happening and ensure it is dealt with accordingly." Maryse smiled at Jem. It was the kind of smile a mother admiring her child's attempt to persuade her would give.

"If you must." She led them to the door, "However I must warn you one of them is rather difficult to work with." A ghost of a smile played on her lips.

Jem inclined his head in way of thanks and gave her a polite smile. "That is quite alright. I am used to dealing with 'difficult' shadowhunters." Jem spared a glance at Will who scowled at him.

"I am _not_ difficult." Will stated, "I simply find teamwork a waste of others efforts. Why involve numerous people when I could have the task done in minutes?" Jem almost laughed. Had they not been in company he would have.

Maryse, however, looked at Will as if what he'd said shocked her. She blinked once before shaking her head as if to clear it of a haze and shut the library door behind her.

Once out in the hallway Church paced up to Jem and resumed his purring and nudging. Maryse stood looking down at the cat in confusion, then up at Jem.

"I…," She swallowed, "You can wait down stairs. I'm sure Church can show you out. The others will be down in a moment."

"Thankyou." Jem smiled as he bent to pick the cat up. Church's purrs grew louder.


End file.
